1. Field of the Invention:
The present invention is directed to a laser treatment apparatus for guiding a laser beam through an optical fiber for the incision, vaporization or coagulation of a target tissue, or for photochemical therapy.
2. Description of the Prior Art:
A well-known laser apparatus for medical treatment has a typical construction depicted in, e.g., FIGS. 8 and 9.
A fiber waveguide member generally designated at 1 includes a core portion 2 and a clad 3. Core portion 2 assumes a substantially circular configuration in cross section and is formed of a light-transmitting material having a low thermal conductivity and a high heat-resistant property such as silica glass or potash glass. Clad 3 is formed on the outer periphery of core portion 2. An output end of core portion 2 is so cut off as to have a surface perpendicular to the optical axis, and is then ground. An input end on the opposite side of core portion 2 is connected to a laser beam source 4. Coaxially provided on the outer periphery of fiber waveguide member 1 is an external tube 6 having a spatial portion 5 serving as, for instance, a water or air passageway. Fixed to the tip of external tube 6 is a holding member 8 formed with an insertion hole 7 into which fiber waveguide member 1 is inserted. An optical connector 9, which is connected to laser beam source 4, is provided at the input end of external tube 6. There is further formed a branch tube 10, the interior of which communicates with spatial portion 5 for sending a liquid or gas to external tube 6. The liquid or gas is fed in from the end of branch tube 10.
The laser beams from laser beam source 4 are led via fiber waveguide member 1 and are then emitted from the output end of the tip of fiber waveguide member 1. At this time, living tissues organized at spacings of several millimeters are irradiated with the laser beams at divergent angles of approximately 8.degree.-12.degree. from the output end of fiber waveguide member 1. On the occasion of irradiation, the irradiation surfaces may be damaged by contaminant such as tissues, tissue liquid and smoke emitted by their vital reaction. With a view to preventing this damage, an assist gas or water is sent from branch tube 10 via spatial portion 5 to the tip output end of fiber waveguide member 1, thereby eliminating the contamination on the output end.
In fact, however, the contamination on the tip end portion can not sufficiently be prevented, depending on the assist gas or water, and the tip end portion is burnt, thereby causing a damage. In order to adjust the divergent angles of laser beams to the purposes of medical treatment, in some cases the tip output end of fiber waveguide member 1 is shaped in a conical or semispherical configuration, but it can easily be damaged by the contamination or diffused rays of light.
FIG. 10 illustrates a known fiber treatment apparatus which effects the medical treatment by directly touching the living. This type of apparatus is arranged such that the tip of holding member 8 of the laser treatment apparatus depicted in FIG. 8 is fitted with a connector 11 connected to a tip member 12 formed of a light-transmitting material like, e.g., artificial sapphire (.alpha.-Al.sub.2 O.sub.3), tip member 12 being so secured to the axis of fiber waveguide member 1 as to be spaced therefrom. Formed in the cylindrical portion of connector 11 around the spacing between tip member 12 and fiber waveguide member 1 are discharge holes 13 from which the assist gas or water is discharged.
There arises, however, the following problem inherent in the laser treatment apparatus depicted in FIG. 10. The apparatus is in contact with the tissues, and hence a contaminant permeates from discharge hole 13 and contaminates the optical axis of tip member 12 as well as fiber waveguide member 1. This results in damage to fiber waveguide member 1 and tip member 12 due to the burnt loss associated with the contaminant by the laser beams.
As described above, the laser treatment apparatus illustrated in FIG. 8 is attended with the problem that the tip end surface of fiber waveguide member 1 undergoes burning due to contamination, resulting in the damage to fiber waveguide member 1.
The laser treatment apparatus also has the problem in which the optical axis positioned in the spacing between fiber waveguide member 1 and tip member 12 is contaminated and undergoes the burning, with the result that the fiber waveguide member 1 and tip member 12 are damaged.
In either case, the contamination has to be eliminated and it is further required that fiber waveguide member 1 be cooled down by using the assist gas or water. Hence, these laser treatment apparatuses are not allowed for use in such places that the assist gas or water can not be employed.